parisc: perf: wire up sys_perf_counter_open

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index ceb68aa..188801b 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -19,6 +19,12 @@
 #define cpu_relax()	asm volatile("" ::: "memory");
 #endif
 
+#ifdef __hppa__
+#include "../../arch/parisc/include/asm/unistd.h"
+#define rmb()		asm volatile("" ::: "memory")
+#define cpu_relax()	asm volatile("" ::: "memory");
+#endif
+
 #include <time.h>
 #include <unistd.h>
 #include <sys/types.h>